New Delhi: A reported bugging of the offices of Finance Minister Pranab Mukherjee and his aides in the North Block has raised the hackles of those in government but an Intelligence Bureau investigation into it had "found nothing in it".

There was no official word on the alleged "security breach" in the offices of the Finance Minister and his aides--Advisor Omita Paul and Private Secretary Manoj Pant--and two conference rooms used by the minister, who had reportedly written to Prime Minister Manmohan Singh in September last year, except a brief statement by Mukherjee.

Mukherjee is said to have urged the Prime Minister to order a secret inquiry into the "serious breach of security in his office" in the form of "planted adhesives" in 16 locationsin a possible surveillance attempt.

No live microphone or recording devices were found, he reportedly said in his letter to the Prime Minister three days after Central Board of Direct Taxes brought in private investigators to conduct an electronic sweep of the Ministry's VVIP chambers.

Confirming a part of the episode, Mukherjee told reporters that the Intelligence Bureau had made investigation into reported bugging in his offices and found "nothing".

"In respect of news item regarding bugging in my offices, the IB investigated into it and found nothing in it," he said without going into any details.

The BJP jumped into the row saying it was serious issue and deserves to be investigated. "This has come at a time when there are so many cases of financial irregularities and scams.

Pranab Mukherjee is number two in the Cabinet.

"Who is bugging its own ministers. It needs to be investigated. It has raised a lot of disturbing questions."

IB, during its investigations, is said to have found that some adhesive type material were spotted in a few places under the table of the Finance Minister and wall of the conference room.

The adhesive material was carefully collected for forensic examination after which it was found that it was nothing other than chewing gum.

The IB, in its report, also said that there was no groove or cavity in places where the chewing gum was spotted, official sources said, adding in one of the places, the adhesive had a paint coating on it suggesting that it had been there for many months.

In the wake of this episode, CBDT inspectors had been regularly conducting electronic sweeps of "sensitive locations" in the finance ministry.